Multi-joint robot with both-side supported arm member

ABSTRACT

In a multi-joint robot ( 1 ) including a first arm member (A 1 ) providing a U-shaped portion ( 10 ) composed of two protrusion units ( 11, 12 ) parallel with each other, and including a second arm member (A 2 ) connected to two protrusion units of the U-shaped portion so as to be rotated and such that both sides of the second arm member are supported by two protrusion units, the first arm member is formed by two half form portions ( 31, 32 ) that are divided between the two protrusion units of the U-shaped portion and are divided on a plane perpendicular to a rotational axis of the second arm member. Moreover, the first arm member includes a coupling unit ( 45   a   , 45   b ) for coupling two half form portions to each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multi-joint robot that includes aboth-side supported arm member.

2. Description of the Related Art

A multi-joint robot including a plurality of joints is widely used. Ageneral multi-joint robot includes a first arm member including aU-shaped portion, and a second arm member connected to the U-shapedportion so as to be rotated. Such an arm member that is referred to as aboth-side supported arm member is disclosed in Japanese UnexaminedPatent Publication No. H07-124886, Japanese Examined Patent PublicationNo. H06-30852, and Japanese Unexamined Patent Publication No. 2011-5635.

Incidentally, the first arm member and the second arm member of themulti-joint robot are manufactured by casting, for example, sandcasting, gravity casting, or die casting. Among these types of casting,die casting is superior in size precision and stability, and is widelyused since low-cost mass production is possible.

FIG. 14A and FIG. 14B are sectional views of dies used in the diecasting. As illustrated in FIG. 14A, when a cast metal C0 is formedbetween the two dies B1 and B2, the dies B1 and B2 are moved in therespective die opening directions and opened, and the cast metal C0 istaken out. On the contrary, in FIG. 14B, undercut portions C1 and C2 areprovided in the cast metal C0. For this reason, the undercut portions C1and C2 become obstacles, so that the one die B2 is not to be opened inthe die opening direction, and accordingly, the cast metal C0 is not tobe taken out.

FIG. 15 is a sectional view of dies for forming the first arm member ofthe multi-joint robot. When the first arm member A1 including theU-shaped portion is formed, a die opening direction of the diesillustrated in FIG. 15 is the same as the direction of the rotationalaxis in a certain case. However, in this case, the U-shaped portions ofthe first arm member A1 correspond to the undercut portions. For thisreason, the dies B1 and B2 are not opened, so that the first arm memberA1 is not to be taken out.

Moreover, the robot houses in a hollow portion inside the arm member,power transmitting elements, for example, a gear and a belt, and aumbilical member, for example, a wiring and a tube. The reason for thisis to prevent the power transmitting elements and the umbilical memberfrom being exposed to the outside. However, in a certain case, dependingon a shape of the hollow portion, the hollow portion may correspond tothe undercut portion, so that the arm member is not to be taken out fromthe die.

For these reasons, in particular, when the arm member of the robot isformed, the sand casting is often adopted instead of the die casting.However, in the sand casting, after casting, the sand die is broken toscrape out the sand. For this reason, in the sand casting, a troublesomework is performed, which leads to an increase in manufacturing cost.

With the view of the above-described problem, the present invention wasmade. An object of the present invention is to provide a multi-jointrobot that can be manufactured by die casting even when a both-sidesupported arm member is formed.

SUMMARY OF THE INVENTION

In order to accomplish the above-described object, according to a firstaspect, there is provided a multi-joint robot that includes a first armmember providing a U-shaped portion formed by two protrusion unitsparallel with each other, and that includes a second arm memberconnected to the two protrusion units of the U-shaped portion so as tobe rotated and such that both sides of the second arm member aresupported by the two protrusion units, wherein the first arm member isformed by two half form portions that are divided between the twoprotrusion units of the U-shaped portion and are divided on a dividingplane perpendicular to a rotational axis of the second arm member, andwherein the first arm member includes a coupling unit for coupling thetwo half form portions to each other.

According to a second aspect, in the first aspect, each of the half formportions is formed by two half form sub-portions that are divided by anadditional plane parallel with the aforesaid dividing plane, and whereineach of the aforesaid half form portions includes an additional couplingunit for coupling the two half form sub-portions to each other.

These object, feature and advantage, and other objects, features andadvantages of the present invention will become more apparent from thedetailed description of the typical embodiments of the present inventionthat are illustrated in the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a multi-joint robot based on the presentinvention;

FIG. 2 is an elevation of a first arm member based on a first embodimentof the present invention;

FIG. 3 is a sectional view of dies for one of half form portions thatconstitutes the first arm member;

FIG. 4 is a perspective view of the two half form portions thatconstitutes the first arm member;

FIG. 5 is an elevation of the first arm member based on a secondembodiment of the present invention;

FIG. 6 is a sectional view of dies for one half form sub-portion thatconstitutes the first arm member;

FIG. 7 is a sectional view of dies for another half form sub-portionthat constitutes the first arm member;

FIG. 8 is a perspective view of four half form sub-portions thatconstitute the first arm member;

FIG. 9 is a perspective view of the first arm member;

FIG. 10 is a partial perspective view seen along the line A-A in FIG. 9;

FIG. 11 is a sectional view of the first arm member and a second armmember according to a certain embodiment;

FIG. 12 is a sectional view of the first arm member and the second armmember according to another embodiment;

FIG. 13 is a sectional view of the first arm member and the second armmember according to a still another embodiment;

FIG. 14A is a sectional view of dies used in die casting;

FIG. 14B is another sectional view of dies used in die casting; and

FIG. 15 is a sectional view of dies for forming a first arm member of amulti-joint robot.

DETAILED DESCRIPTION

In the following, the embodiments of the present invention will bedescribed with reference to the drawings. In the following drawings, thesame reference symbols are given to the same members. To facilitateunderstanding, reduced scales in these drawings are appropriatelychanged.

FIG. 1 is a perspective view of a multi-joint robot based on the presentinvention. As illustrated in FIG. 1, the multi-joint robot 1 includes aplurality of arm members. The first arm member A1 among such a pluralityof arm members as these includes a U-shaped portion 10. The second armmember A2 is connected to the U-shaped portion 10 of the first armmember A1 so as to be rotated. Moreover, in FIG. 1, the rotational axisO of the second arm member A2 is illustrated.

FIG. 2 is an elevation of the first arm member based on a firstembodiment of the present invention. The U-shaped portion 10 of thefirst arm member A1 includes two protrusion units 11 and 12 parallelwith each other. In FIG. 2, at a center between these protrusion units11 and 12, a plane P1 is illustrated. This plane P1 extends in adirection approximately perpendicular to the rotational axis O (refer toFIG. 1) of the second arm member A2. Two portions formed by dividing thefirst arm member A1 with the plane P1 are called half form portions 31and 32.

FIG. 3 is a sectional view of dies for one of the half form portionsthat constitutes the first arm member, and according to the firstembodiment, the half form portions 31 and 32 are formed by die casting.In FIG. 3, the dies B1 and B2 for the one half form portion 31 areillustrated. The boundary plane between the dies B1 and B2 is at theposition corresponding to an inner wall of the protrusion unit 11. Whenthe dies B1 and B2 are thus arranged, an undercut portion is notproduced in the half form portion 31. Accordingly, the dies B1 and B2can be opened in the same direction as the direction of the rotationalaxis O so that the half form portion 31 can be taken out. The samedescription applies to the other half form portion 32.

Thereby, as illustrated in FIG. 4, the two half form portions 31 and 32are formed. As can be seen from FIG. 4, a concave portion for housingpower transmitting elements and a umbilical member is formed in each ofthe half form portions 31 and 32 in the inside thereof. These half formportions 31 and 32 are assembled to form the first arm member A1, and,the above-described concave portions form the hollow portion inside thefirst arm member A1.

FIG. 5 is an elevation of the first arm member based on a secondembodiment of the present invention. In FIG. 5, in addition to theabove-described plane P1, the additional planes P2 and P3 that passthrough approximately the middle positions of the protrusion units 11and 12 are illustrated respectively. As can be seen from the drawing,these additional planes P2 and P3 are parallel with the plane P1. Fourportions formed by dividing the first arm member A1 with the plane P1and the additional planes P2 and P3 are called half form sub-portions 41a, 41 b, 42 a and 42 b. Moreover, it would be understood that the twohalf form sub-portions 41 a and 41 b correspond to the half form portion31, and the two half form sub-portions 42 a and 42 b correspond to thehalf form portion 32.

FIG. 6 is a sectional view of dies for the one half form sub-portionthat constitutes the first arm member, and according to the secondembodiment, the half form sub-portion 41 a is formed by die casting. InFIG. 6, dies B3 and B4 for the one half form sub-portion 41 a areillustrated. The boundary plane between the dies B3 and B4 is at theposition corresponding to an inner wall of the protrusion unit 11. Whensuch dies B3 and B4 are thus arranged, an undercut portion is notproduced in the half form sub-portion 41 a. Accordingly, the dies B3 andB4 can be opened in the same direction as the direction of therotational axis O so that the half form sub-portion 41 a can be takenout. The same description as for the half form sub-portion 41 a appliesto the other half form sub-portion 42 a.

FIG. 7 is a sectional view of dies for another half form sub-portionthat constitutes the first arm member, and according to the secondembodiment, the half form sub-portion 41 b is formed by die casting. InFIG. 7, the dies B5 and B6 for the other half form sub-portion 41 b areillustrated. The boundary plane between the dies B5 and B6 is at theposition corresponding to an approximately center of the protrusion unit11. When dies B5 and B6 are thus arranged, an undercut portion is notproduced in the half form sub-portion 41 b. Accordingly, the dies B5 andB6 can be opened in the same direction as the direction of therotational axis O so that the half form sub-portion 41 b can be takenout. The same description as for the half form sub-portion 41 b appliesto the other half form sub-portion 42 b.

Thereby, as illustrated in FIG. 8, the four half form sub-portions 41 a,41 b, 42 a and 42 b are formed. As can be seen from FIG. 8, a hollowportion or a concave portion for housing power transmitting elements anda umbilical member is formed in each of the half form sub-portions 41 a,41 b, 42 a and 42 b in the inside thereof. These half form sub-portions41 a, 41 b, 42 a and 42 b are assembled to form the first arm member A1,and the above-described concave portions form the hollow portion insidethe first arm member A1.

FIG. 9 is a perspective view of the first arm member. The first armmember illustrated in FIG. 9 is constituted by the half formsub-portions 41 a, 41 b, 42 a and 42 b. The half form sub-portion 42 aand the half form sub-portion 42 b are coupled to each other by shortbolts 45 a. This description applies to the half form sub-portion 41 aand the half form sub-portion 41 b. Further, the half form sub-portion41 a and the half form sub-portion 42 a are coupled to each other bylong bolts 45 b. These short bolts 45 a and the long bolts 45 b functionas a coupling unit.

In addition, in the same manner, the half form portions 31 and 32 areassembled to form the first arm member A1. In this case, however, notethat the long bolts are used (refer to FIG. 4).

FIG. 10 is a partial perspective view seen along the line A-A in FIG. 9.As illustrated in FIG. 10, at a coupling portion between the half formsub-portion 41 a and the half form sub-portion 42 a, aligning pins 47are provided. These aligning pins 47 can improve aligning precision.Further, seal members such as O-rings and packing not illustrated in thedrawings may be arranged on respective coupling surfaces between thehalf form sub-portions 41 a, 41 b, 42 a and 42 b. Alternatively, sealingagents not illustrated in the drawings may be applied to the couplingsurfaces. Thereby, a waterproofing function can be given to the firstarm member A1 of the robot.

Thus, according to the present invention, the first arm member A1 of theboth-side supported type can be formed by die casting. In other words,according to the present invention, as it is not necessary to performthe sand casting, the multi-joint robot 1 including the high-quality armmember A1 can be mass-produced at low cost while manufacturing cost canbe suppressed.

Thus, according to the first embodiment, the first arm member A1including the U-shaped portion is divided by the above-mentioned planeP1 to form the half form portions 31 and 32. By arranging the dies suchthat an undercut portion are not included, these half form portions 31and 32 can be formed by die casting to produce the first arm member A1.

Further, according to the second embodiment, the one half form portion31 is constituted by the two half form sub-portions 41 a and 41 b, forexample. Accordingly, it would be understood that the first arm memberA1 having a more complicated shape can be produced with ease and at lowcost.

FIG. 11 is a sectional view of the first arm member and the second armmember according to a certain embodiment. As illustrated in FIG. 11, atone protrusion unit 11 of the first arm member A1, a speed reducer 51 isarranged. At the other protrusion unit 12, a bearing 52 is arranged.With this configuration, the second arm member A2 is sandwiched betweenthe protrusion units 11 and 12 such that the second arm member A2 can besupported at the protrusion unit 11 by the speed reducer 51 and thebearing 52 so as to be rotated. Adopting such a both-side supportingconfiguration can make rigidity at a joint axis higher than that in acantilever configuration. For this reason, a positional precision at thetip of the multi-joint robot 1 can be improved.

In case of the multi-joint robot 1 possessing a waterproofing function,as illustrated in FIG. 11, an oil seal 53 may be arranged around thebearing 52, or a waterproofing function may be given to the bearing 52.Thereby, it is possible to prevent water from entering the inside of themulti-joint robot 1 through the joint axis.

Moreover, in FIG. 11, below the U-shaped portion 10, a motor M isarranged. An output shaft of the motor M is connected to the speedreducer 51 by the power transmitting elements such as gears and a belt55 that are arranged inside the protrusion unit 11. By the way,generally, the fine adjustment of the positions of the gears and thebelt 55 is necessary to improve the positional precision of themulti-joint robot 1. When the first arm member A1 is constituted by fourhalf form sub-portions 41 a, 41 b, 42 a and 42 b as described abovereferring to FIG. 8 and the like, only the outside half form sub-portion41 b, for example, is detached, then the gears and the belt 55 can beeasily accessed. For this reason, according to the present invention, itis possible to improve the efficiency of adjusting positions of thegears and the belt 55.

Furthermore, in FIG. 11, the umbilical member 57, for example, a cablefor a motor (not illustrated) arranged on the tip side of the second armmember A2, or an air tube for driving a hand (not illustrated)positioned at the tip of the multi-joint robot 1 is illustrated. Suchumbilical members 57 are arranged so as to pass the inside of theprotrusion unit 12 of the first arm member A1 through the bearing 52from the second arm member A2. Accordingly, it is possible to keep theumbilical members 57 from being exposed to the outside of themulti-joint robot 1. The work of arranging such umbilical members 57 canbe performed by detaching the outside half form sub-portion 42 b only,for example. For this reason, according to the present invention, it ispossible to improve the efficiency in work of arranging the umbilicalmembers 57.

Further, when the speed reducer 51 having a hollow configuration isadopted, the umbilical members 57 can be arranged on the side of theprotrusion unit 11. In such a case, the umbilical members 57 and theabove-described power transmitting elements, for example the gears andthe belt 55, are arranged in the same protrusion unit 11. Accordingly,by detaching one outside half form sub-portion 41 b only enables both ofadjusting the positions of the gears and the belt 55, and arranging theumbilical members 57.

FIG. 12 is a sectional view of the first arm member and the second armmember according to another embodiment. In FIG. 12, two motors M1 and M2are arranged below the U-shaped portion 10. An output shaft of motor M1is connected to the speed reducer 51 by the power transmitting elements,for example, the gears and the belt 55 that are arranged inside theprotrusion unit 11. The other output shaft of motor M2 is connected to adriven portion in the second arm member A2 by power transmittingelements, for example, gears and a belt 56 that are arranged inside theprotrusion unit 12. Even in such a configuration, the adoption of thespeed reducer 51 having a hollow configuration enables the powertransmitting elements, for example, the gears and the belts 55 and 56,to be arranged inside the same protrusion unit 11. It would be apparentthat even in such a case, the same advantage as described above can beobtained.

FIG. 13 is a sectional view of the first arm member and the second armmember according to a still another embodiment. In FIG. 13, the motor Mis arranged inside the second arm member A2, and connected directly tothe speed reducer 51. In such a case, the power transmitting elements,for example, the gears and the belt 55 can be excluded from a spaceinside the protrusion unit 11.

ADVANTAGES OF THE INVENTION

According to a first aspect, the half form portions are formed bydividing the first arm member including the U-shaped portion by theabove-described plane. By arranging the dies not to include the undercutportions, the half form portions are formed by the die casting to formthe first arm member. In other words, according to the presentinvention, a sand casting does not need to be performed, so that therobot including the high-quality arm member can be mass-produced at lowcost while manufacturing cost can be suppressed.

According to s second aspect, the half form portion is constituted bythe two half form sub-portions, so that the first arm member having amore complicated shape can be produced with ease and at low cost.

The typical embodiments were used for describing the present invention,a person skilled in the art, however, would understand that theabove-described alteration and various types of other alteration,omission and addition can be performed without departing from the scopeof the present invention.

1. A multi-joint robot that comprising a first arm member providing aU-shaped portion formed by two protrusion units parallel with eachother, and a second arm member connected to two protrusion units of theU-shaped portion so as to be rotated and such that both sides of thesecond arm member are supported by the two protrusion units, wherein thefirst arm member is formed by two half form portions that are dividedbetween the two protrusion units of the U-shaped portion and are dividedon a dividing plane perpendicular to a rotational axis of the second armmember, and wherein the first arm member includes a coupling unit forcoupling the two half form portions to each other.
 2. The multi-jointrobot according to claim 1, wherein each of the half form portions isformed by two half form sub-portions that are divided by an additionalplane parallel with the dividing plane, and wherein each of the halfform portions includes an additional coupling unit for coupling the twohalf form sub-portions to each other.